[1] Dalhousie Univ, Dept Phys & Atmospher Sci, Halifax, NS B3H 3J5, Canada
[2] Dalhousie Univ, Mat Res Inst, Halifax, NS B3H 1W5, Canada
[3] Dalhousie Univ, Dept Chem, Halifax, NS B3H 4J3, Canada
[4] Natl Res Council Canada, Steacie Inst Mol Sci, Ottawa, ON K1A 0R6, Canada